BIOS 1700 Ch. 8 Photosynthesis

Which of the following is part of the photosynthetic electron transport chain between photosystems I and II? A. All of these choices are correct. B. plastocyanin C. plastoquinone D. cytochrome-b6f complex

A. All of these choices are correct.

Which of the following is true when comparing the Calvin cycle and light-harvesting reactions of photosynthesis? A. NADPH B. NADP+ C. ADP D. Glucose E. Sucrose

A. NADPH

How many molecules of NADPH are required for 12 molecules of RuBP to be carboxylated by rubisco? A. None of the answers are correct B. 12 C. 10 D. 36 E. 24

A. None of the answers are correct

The regeneration of RuBP typically limits the rate of photosynthesis under low light intensities. This is because: A. RuBP regeneration requires ATP B. RuBP regeneration requires ADP C. RuBP regeneration is part of the "dark reactions" D. photosynthesis occurs only in high light E. None of the answers are correct

A. RuBP regeneration requires ATP

Assuming that all is working properly in photosynthesis, which of the following is at a higher energy level? A. an excited-state antenna chlorophyll molecule B. an excited-state reaction center chlorophyll

A. an excited-state antenna chlorophyll molecule

The Z scheme is a model for the interpretation of: A. the changes in the energy level of electrons as they pass through the photosynthetic electron transport chain. B. proton translocation. C. electron transport. D. the path of electrons between photosystem II and cytochrome b6f. E. the use of H2O as an electron source.

A. the changes in the energy level of electrons as they pass through the photosynthetic electron transport chain.

Which of the following is true when comparing the Calvin cycle and light-harvesting reactions of photosynthesis? A. They take place in different compartments of the same organelle B. They take place in different organelles C. They take place in different types of cells in the plant D. None of the other answer options are correct

A. they take place in different compartments of the same organelle

Which of the following is needed directly to produce both triose phosphates and RuBP in the Calvin cycle? A. PS II B. ATP C. Rubisco D. O2 E. NADPH

B. ATP

From its ground state, photosystem II can: A. emit light energy B. absorb light energy C. pull protons from H2O D. pull electrons from H2O E. pass electrons to photosystem I

B. absorb light energy

Rubisco is characterized by: A. the ability to use three substrates B. slow catalysis and the ability to use two substrates C. the ability to use three substrates and faster catalysis D. fast catalysis

B. slow catalysis and the ability to use two substrates

Photosystem I is a _____ than photosystem II. A. weaker oxidant and weaker reductant B. weaker oxidant and a stronger reductant C. stronger oxidant and a stronger reductant D. stronger oxidant E. weaker reductant

B. weaker oxidant and a stronger reductant

How does the metabolism occurring in chloroplasts differ from that of mitochondria? A. different proton sources B. None of the answers are correct C. different electron acceptors and electron sources D. different proton acceptors E. one makes ATP, the other makes NADPH

C. different electron acceptors and electron sources

NADPH production in photosynthesis requires: A. light and protons only. B. electrons only. C. light, electrons, and protons. D. light only. E. protons only.

C. light, electrons, and protons.

For every six CO2 molecules incorporated into carbohydrate molecules, how many triose phosphates can be exported from the chloroplast? A. 6 B. 12 C. 1 D. 2 E. 10

D. 2

Which of these are products of the light-dependent reactions of photosynthesis that are required by reactions in the Calvin cycle? A. NADP+ and O2 B. ATP and O2 C. H2O and NADPH D. ATP and NADPH

D. ATP and NADPH

In addition to chlorophylls, light-harvesting antennae include other pigments. What is the benefit of these additional pigments? A. lower antioxidant capacity B. enhanced resonance transfer C. increased structural stability of the antennae D. increased range of wavelengths absorbed E. tighter binding of the antennae to the thylakoid

D. Increased range of wavelengths absorbed

Cyclic electron transport enhances ATP production because: A. cyclic electron transport is more energy efficient than linear electron transport. B. protons are recycled into the thylakoid lumen. C. the cycling of ADP to ATP is enhanced by transport. D. excited electrons are transferred from PS I back to plastoquinone. E. photosystem I can pump more protons into the thylakoid lumen.

D. excited electrons are transferred from PS I back to plastoquinone.

Many photosynthetic prokaryotes are capable of cyclic electron transport only. It is likely that such organisms can _____ but not _____. A.reduce CO2; synthesize carbohydrates B. produce ATP; reduce H2O C. produce NADPH; reduce CO2 D. produce ATP; reduce CO2 E. produce NADPH; oxidize H2O

D. produce ATP; reduce CO2

Which of these is responsible for the transport of electrons between photosystem II and photosystem I? A. NADP+ B. chlorophyll C. NADPH D. H2O E. cytochrome b6f

E. cytochrome b6f

Chemicals called uncouplers can make membranes permeable to small molecules and ions. What effect might uncouplers have on photosynthesis? A. decreased NADPH production because the proton gradient would increase B. decreased ATP production because the proton gradient would increase C. increased ATP production because cyclic electron transport would increase D. decreased NADPH production because the proton gradient would decrease E. decreased ATP production because the proton gradient would decrease

E. decreased ATP production because the proton gradient would decrease

Antennae work with reaction centers by providing: A. fluorescence. B. electron transfer. C. heat loss. D. H+ transfer. E. energy transfer.

E. energy transfer

T/F: The Calvin cycle is a relatively constant process, the rate of which is independent of factors such as temperature and nitrogen concentration.

False

Which compound is required for the carboxylation step of the Calvin cycle?

RuBP

T/F: The products of the Calvin cycle are 3-carbon sugars.

True

In the Calvin cycle, ATP is required to:

donate a phosphate group to 3-PGA.

Excessive reactive oxygen species (ROS) can cause damage to cells. What is a cause of ROS formation during photosynthesis?

high energy electrons are unable to be passed to NADP+

ATP production in photosynthesis requires:

light, electrons, and protons

In the Calvin cycle, NADPH is:

oxidized

Which step of the Calvin cycle would be affected first by a lack of NADPH?

reduction

Photosynthesis is the pathway used to synthesize carbohydrates from:

sunlight, CO2, and H2O

A researcher is carrying out an experiment where she labels a protein with a fluorescent tag (so she can visualize its location in a cell) and introduces this tagged protein into the lumen of a single thylakoid. She observes her treated cells periodically and notices that the labeled protein can move between grana and is always in the lumen, but is never observed in the stroma. What can she deduce?

the protein likely travels through a common lumen shared by thylakoid membranes and grana, and cannot easily diffuse through the thylakoid membrane

Suppose a plant is exposed to a toxin that causes the thylakoid membranes to become much more permeable to protons than normal. Which of the following would be true?

the reduction and regeneration steps of the Calvin cycle would slow down and eventually stop